Typically atmospheric fryers and vacuum fryers have a number of zones through which product passes to be fried. The fryers including a frying kettle that receives the heated oil, with the kettle having an inlet end and a drained end between which the oil flows, with the oil passing from the outlet end to the inlet end through pumps, filters and heaters.
A conveyor delivers product to the upstream end of the kettle so that the product flows with the oil in a downstream direction. Along the length of the kettle there is usually provided paddles that enter the oil stream and move with the oil stream to aid in moving the product in a downstream direction.
A vacuum fryer is described in International Patent Application PCT/NL2006/000051 (International Patent Publication WO 2007/086724).
Previous continuous fryers have suffered from a number of disadvantages including inconsistently frying the product as a result of high dwell time deviations. This can lead to quality reduction and quality consistency in respect of the product. For example, the natural taste of the product, such as potato, may be degraded, the product may be distorted in shape, while some of the product may have a raised acrylamide content. Other disadvantages are: fatty chips (over fried), increased amounts of small product parts in the fryer that lead to oil quality problems, and longer cleaning times.